CT Colonography: Performance and Program Outcome Measures in an Older Screening Population 1
Department of Radiology, University of Wisconsin School of Medicine and Public Health, E3/311 Clinical Science Center, 600 Highland Ave, Madison, WI 53792-3252, USA. Radiology
(Impact Factor: 6.87).
02/2010; 254(2):493-500. DOI: 10.1148/radiol.09091478
To evaluate computed tomographic (CT) colonography performance and program outcome measures in an older cohort (65-79 years) of an established large-scale colorectal cancer screening program.
This HIPAA-compliant study was approved by the institutional review board; informed consent waived. Retrospective analysis of the 65-79-year-old cohort (n = 577) from the University of Wisconsin CT colonography screening program (n = 5176) was undertaken. Performance and outcome measures including advanced neoplasia prevalence and colonoscopy referral, extracolonic finding, extracolonic work-up, and complication rates were obtained by using a CT colonography database and review of medical records. Comparisons between the older cohort and the general screening population were made by using the Student t, Pearson chi(2), and Fisher exact tests. A P value <or= .05 was considered to indicate a significant difference.
With a 6-mm threshold for positivity, the overall referral rate to optical colonoscopy was 15.3% (88 of 577), leading to 277 polypectomies and the removal of 103 nondiminutive adenomas. For adenomas, the per-patient positivity rates were 10.9% (63 of 577) and 6.8% (39 of 577) at the 6- and 10-mm thresholds, respectively. The prevalence of advanced neoplasia was 7.6% (44 of 577). Fifty-four adenomas met advanced status, and five unsuspected cancers were detected. The advanced neoplasias identified were typically large, with a mean size of 21 mm. Potentially important extracolonic findings were seen in 15.4% (89 of 577) of patients, with a work-up rate of 7.8% (45 of 577). The majority of important extracolonic diagnoses were vascular aneurysms (n = 18). No major complications were encountered.
CT colonography is a safe and effective screening modality for the older population.
Available from: sciencedirect.com
- "Our analyses suggest that patients who undergo initial CTC, with or without subsequent OC, may experience lower rates of serious gastrointestinal, other gastrointestinal and cardiovascular events compared to patients who receive initial OC. This finding is intuitively reasonable, given that CTC does not require sedation and the intention of CTC is to selectively refer the approximately 8–15% of patients with suspected clinically significant polyps (N6 mm) and masses to OC for further evaluation (Kim et al., 2007, 2010; Macari et al., 2011). However, it is important to recognize that we were unable to fully adjust for differences between the groups based upon the information available in claims data. "
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ABSTRACT: To evaluate gastrointestinal and cardiovascular adverse event risks associated with optical colonoscopy (OC) among Medicare outpatients who received computed tomography colonography (CTC) as their initial method of colorectal evaluation.
Medicare claims were compared between 6,114 outpatients ≥ 66 years who received initial CTC and 149,202 outpatients who received initial OC between January 2007 and December 2008. OC patients were matched on county of residence and year of evaluation. Outcomes included lower gastrointestinal bleeding, gastrointestinal perforation, other gastrointestinal events and cardiovascular events resulting in an emergency department visit or hospitalization within 30 days.
Among 1,000 outpatients undergoing initial CTC, 12.4 experienced lower gastrointestinal bleeding, 0.7 perforation, 18.0 other gastrointestinal events and 45.5 cardiovascular events within 30 days. After multivariate adjustment, risks of lower gastrointestinal bleeding, other gastrointestinal events and cardiovascular events were higher with initial OC than CTC, with or without subsequent OC (OR 1.91 95CI [1.47,2.49], OR 1.35 95CI [1.07,1.69] and OR 1.38 95CI [1.18,1.62], respectively); however, perforation risk did not differ (p=0.10). This pattern is similar in older and symptomatic populations.
Rates of gastrointestinal bleeding, other gastrointestinal events and cardiovascular events are lower following initial CTC than OC, but rates of perforation do not differ.
Available from: Judy Yee
- "CTC performance has been evaluated in senior patient cohorts (age 65 years). A retrospective analysis of 577 subjects found an excellent CTCecolonoscopy concordance rate of 91%. Based on a 6-mm threshold, there was an overall patient referral rate of 15% for colonoscopy. "
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ABSTRACT: Colorectal cancer is the third leading cause of cancer deaths in the United States. Most colorectal cancers can be prevented by detecting and removing the precursor adenomatous polyp. Individual risk factors for the development of colorectal cancer will influence the particular choice of screening tool. CT colonography (CTC) is the primary imaging test for colorectal cancer screening in average-risk individuals, whereas the double-contrast barium enema (DCBE) is now considered to be a test that may be appropriate, particularly in settings where CTC is unavailable. Single-contrast barium enema has a lower performance profile and is indicated for screening only when CTC and DCBE are not available. CTC is also the preferred test for colon evaluation following an incomplete colonoscopy. Imaging tests including CTC and DCBE are not indicated for colorectal cancer screening in high-risk patients with polyposis syndromes or inflammatory bowel disease. This paper presents the updated colorectal cancer imaging test ratings and is the result of evidence-based consensus by the ACR Appropriateness Criteria Expert Panel on Gastrointestinal Imaging. The ACR Appropriateness Criteria are evidence-based guidelines for specific clinical conditions that are reviewed every 2 years by a multidisciplinary expert panel. The guideline development and review include an extensive analysis of current medical literature from peer-reviewed journals and the application of a well-established consensus methodology (modified Delphi) to rate the appropriateness of imaging and treatment procedures by the panel. In those instances where evidence is lacking or not definitive, expert opinion may be used to recommend imaging or treatment.
Available from: jocoleman.info
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ABSTRACT: A major drawback of delta-sigma modulation is the high oversampling ratios required, especially for single-bit quantization. Accordingly, much of the research in the area has focused on lowering the sampling rate through various parallelization approaches. However, this research has been overwhelmingly concentrated on continuous and discrete-time analog modulator implementations for A/D converters, and not on reducing the critical path in a digital implementation for D/A conversion. In this paper the popular time-interleaved modulator is paired with a vector quantizer implementation of a finite-length modulator to form a parallel implementation of a delta-sigma DAC with a reduced critical path.
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